Abstract: A processing module to monitor a horizontal delay gradient in satellite signals is provided. The processing module includes a dual-processing-satellite-differencing module, a double differencing module, and a gradient estimator module. The dual-processing-satellite-differencing module is operable to: receive carrier phase measurements for at least two satellites from at least two reference receivers; implement a first processing mode to normalize first satellite differences between +?/2 and ??/2; implement a second processing mode configured to normalize second satellite differences between 0 and ?; and select for further processing one of: data indicative of the first satellite differences processed according to the first processing mode; and data indicative of the second satellite differences processed according to the second processing mode. The double differencing module forms double-differences based on the selected data input from the dual-processing-satellite-differencing module.

Abstract: Systems and methods to monitor for false alarms from ionosphere gradient monitors are provided. In one embodiment, a method for mitigating false gradient alarms in a satellite navigation Ground Based Augmentation System (GBAS) ground station comprising a plurality of satellite navigation system reference receivers comprises: generating an alarm signal with an ionosphere gradient monitor (IGM) at the GBAS ground station; determining whether the alarm signal is a false alarm based on data derived from carrier phase measurements received from the plurality of satellite navigation system reference receivers; and blocking the alarm signal for at least a first duration of time based on the determining.

Abstract: A processing function to monitor a horizontal delay gradient in satellite signals is provided. The processing function includes a satellite differencing module, a double differencing module, a parity test module, and a gradient estimator module. The satellite differencing module receives carrier phase measurements for at least two satellites from at least three reference receivers. The satellite differencing module determines differences in the carrier phase measurements between signals from the monitored satellite and at least one of the at least one other satellite. The double differencing module: forms double-differences between pairs of the reference receivers; compensates the double-differences between the pairs; performs a modulo operation; and averages the double differences. The parity test module inputs the averaged compensated double differences when the average exceeds a parity enable threshold. The gradient estimator module configured is to estimate a magnitude of the horizontal delay gradient.

Abstract: A processing module to monitor a horizontal delay gradient in satellite signals is provided. The processing module includes a dual-processing-satellite-differencing module, a double differencing module, and a gradient estimator module. The dual-processing-satellite-differencing module is operable to: receive carrier phase measurements for at least two satellites from at least two reference receivers; implement a first processing mode to normalize first satellite differences between +?/2 and ??/2; implement a second processing mode configured to normalize second satellite differences between 0 and ?; and select for further processing one of: data indicative of the first satellite differences processed according to the first processing mode; and data indicative of the second satellite differences processed according to the second processing mode. The double differencing module forms double-differences based on the selected data input from the dual-processing-satellite-differencing module.

Abstract: A processing function to monitor a horizontal delay gradient in satellite signals is provided. The processing function includes a satellite differencing module, a double differencing module, a parity test module, and a gradient estimator module. The satellite differencing module receives carrier phase measurements for at least two satellites from at least three reference receivers. The satellite differencing module determines differences in the carrier phase measurements between signals from the monitored satellite and at least one of the at least one other satellite. The double differencing module: forms double-differences between pairs of the reference receivers; compensates the double-differences between the pairs; performs a modulo operation; and averages the double differences. The parity test module inputs the averaged compensated double differences when the average exceeds a parity enable threshold. The gradient estimator module configured is to estimate a magnitude of the horizontal delay gradient.

Abstract: Systems and methods to monitor for false alarms from ionosphere gradient monitors are provided. In one embodiment, a method for mitigating false gradient alarms in a satellite navigation Ground Based Augmentation System (GBAS) ground station comprising a plurality of satellite navigation system reference receivers comprises: generating an alarm signal with an ionosphere gradient monitor (IGM) at the GBAS ground station; determining whether the alarm signal is a false alarm based on data derived from carrier phase measurements received from the plurality of satellite navigation system reference receivers; and blocking the alarm signal for at least a first duration of time based on the determining.